Dashpot controlled switch



"Mar. 2@, 11923.

G. o. WILMS DASHPOT CONTROLLED SWITCH Filed Feb. 20, 1920 Patented Mar, 20, teas UNHTEED) g ANT c,

GUSTAV O. WILKES, OlF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE RELIANCE COMPANY OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

DASHPOT CONTROLLED SWITCH.

Application filed. February 20, 1920. Serial No. 360,098. i

To all whom it may concern:

Be it known that I, GUSTAV O. WILMS, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented certain new and useful Improvements in Dashpot Controlled Switches; and I do hereby declare that the following is a full, clear, and exact description thereof.

My invention relates to new and useful improvements in dash-pot controlled mechanisms and is more particularly directed to the provision of a dash-pot controlled electric switch of that type wherein the movable switch member is operable by magnetic means, and controlled in such operation by the dash-pot mechanism to provide a time 'factor in the operation of the switch,

the present embodiment of my invention being particularly adapted for use in a motor circuit to open the circuit upon serious conditions of overload, but permitting the occurrence of temporary, trivial increases of current without affecting the operation of the switch.

'It is in general the object of my invention to simplify and otherwise improve the structure and to increase the efliciency of devices of this character, and the convenience with which said devices may be adjusted for the various conditions of use under which they would be desired to operate.

It is more particularly an important object of my invention to provide a dash-pot arrangement, having its parts so related as to avoid the necessity of very accurate fitting surfaces, whereby, if desired, the parts i the switch and whereby to facilitate a most may be simply die cast to procure their interfitting relation, and whereby the plunger of the dash-pot piston is, permitted a certain slightlater,al looseness to eliminate the possibility of said plunger binding against the parts which would be engaged in its path of movement, the plunger constituting, in the present instance, the armature ofthe switch operating solenoid.

A further important object resides in the provision of a dash-pot structure having its parts so arranged as to procure a desired prolonged detent action, with an exceedingly short stroke of the piston member, whereby a desired compactness of structure is procured, and whereby, with respect to the switch operating solenoid, a maximum adnet justment of the armature core therein may be permitted, so as to provide for desired operation of the switch mechanism under a wide range of current conditions.

pendent manipulation to permit the adjustment.

A still further object with respect to the desired short stroke of the dash-pot piston, resides in the provision of a multiplicity of co-acting dash-pot chambers, provided with common means for controlling the flow of fluid with respect thereto.

A still further object resides in the provision of an arrangement wherein the fluid of the dash-pot is caused to travel in a tortuous path incidental to movement of the piston whereby to increase the retarding action by reason of the inertia of the fluid in changing its directions of flow incidental to its travel in such tortuous path.

A still. further object residesinthe provision of means for releasing the detent action of the dash-pot at a desired limit of such detent action, whereby to then permit a free snapping movement of the piston stem of the dash-pot for its desired operation to procure a quick-break operation of With the above and other objects and Y advantages in view, my invention resides more particularly 1n the novel combination, formation and arrangement of parts hereinafter described and pointed out in the Figure 2 1s a vertical, longitudinal, secmechanism.

Figure 4 is a bottom view of the dash-pot piston.

- Figure 5 is a plan view of the dash-pot cylinder.

Figure 6 is a detailed sectional view through the armature plunger on a plane indicated by the line 6-6 of Figure 2.

Figure 7 is a detailed sectional view showing the means for detachably securing the dash-pot cylinder in place.

Referring now more particularly to the drawings, in the present embodiment of my invention, the various parts are carried by a frame formed of a metallic strap 10, bent in substantially rectangular shape and provided with attaching bolt holes in the ends of the frame. A solenoid coil 11 has its conventionally shown convolutions disposed between the sides of the frame and wound upon a coresleeve 12, which has one end projected through. one side of the frame to provide an annular holding shoulder, the usual end plates 13 of the coil being engaged against the inner sides of the frame. A bushing member 1 1 is fitted within the other end of the core sleeve and extends through the other side of the frame. A tappet pin 15 is slidably mounted in the bushing and extends through an insulated block 16 disposed on the adjacent side of the frame, said side of the frame being disposed uppermost in the present embodiment of my invention.

The stationary contact member of the switch comprises a plate 17, secured on one end of the insulating block by a binding post 18, the contact portion of the. plate being inclined obliquely outward. The movable contact member comprises, in the present instance, a length of wire 19, doubled upon itself and having its end portions oppositely coiled on a bolt 20,- carried by upstanding ears 21 on the remote end portion of, the

insulating. block, the terminals of said wires belng directed inwardly and engaging the block to prevent rotatibn of the coil portions of the bolt, and said wire possesses considerable resilience, whereby its bent portion, constituting the free end of the movable contact member, is resiliently urged toward the stationary contact plate 17 the wire lengths beingtwisted adjacent their central bend, whereby to hold a contactbutton 22 for engagement with the plate. The intermediate portions of the wire lengths are oppositely bowed to fit the grooved head portion of the tappetpin 15, whereby outward movement of the tappet pin, upon engagement by an armature core 5 within the solenoid, will open the switch. i

This armature core of thesolenoid, which will be later described in detail, comprises the piston stem of a dash-pot arrangement, including a cylinder 23, having an integral bottom closure,and provided with a top closure plate 24, having its peripheral portion pressed downwardly and then upwardly at its extremity, to define a flange frictionally engaging in the upper end of the cylinder 23, the closure plate being provided with a central plunger aperture and having its portions surrounding said aperture depressed to form a shoulder adapted to engage about the shoulder of the frame, formed in the present instance, by the projected end of the core sleeve 12, whereby to properly center the dash-pot cylinder in its assembled position. The dash-pot is detachably held against the frame by single "length of spring wire, bent in substantially portions of the lower side of the frame The legs of the yoke are sinuously bent to permit resilient extension thereof, and the bight portion of the yoke is engageable in central recesses formed in a pair of ribs 27 on the bottom of the dash-pot cylinder, said ribs being curved to provide slide surfaces for the bight of the yoke, and the central portion of the bight is outwardly bent between its rib engaging portions to form a finger piece 28. The yoke will move from the recessed portions of the ribsupon lateral pressure on finger piece 28, and thus the dash-pot cylinder may be most readily assembled or disassembled with respect to the frame by swinging the retaining yoke on the pivots afforded by its pintle ends.

The bottom of the dash-pot is provided dash-pot cylinder, and a piston 30 is loosely fitted within the dash-pot cylinder and carries a plurality of depending wall sections 31, adapted to loosely fit between the wall sections 29 and the main wall of the cylinder, said piston alsocarrying a depending central projection 32 'engageable in the space bounded by the inner cylinder wall section 29. A pair of upper dash pot chambers are thus defined at the tops of walls 29, which increase in volume as-the piston is drawn upwardly, and a pair of dash-pot chambers are defined at the bottoms of the walls 31, together with a third chamber defined at the bottom of the central projection 32 of the piston. Intake ports 33 extend through the piston and communicate with the upper dash-pot chambers, while relatively large therein, are also extended through the piston and communicate with these chambers,

the balls being held in place by a plate 36 projecting over portions of the exhaust ports.

A common control for the intake ports 33 is afforded by a valve plate 37, pivoted centrally on the piston between the ports and having edge portions projecting over the ports, said plate bein movable against considerable friction resistance to thus adjust the flow capacity of the inlet ports and procure a corresponding adjustment of the time interval of operation of the dash-pot upon a given pull. By reason of the loose fit between the various wall sections, any suitable fluid which is provided for the dash-pot will pass through the ports 33 in lifting movement of the piston and will then flow laterally in the upper, dash-pot chambers and pass between the opposed surfaces of the various wall portions into the lower dash-pot the walls. A tortuous path is thus afiorded for the fluid in the retarding operation of the dash-pot parts, whereby to materially increase such retarding action by reason of the inertia and .increased friction of the fluid in following such tortuous paths.

The interior. of the dash-pot cylinder is provided .with longitudinal channels 38, extending from its top to a point adjacent the tops of the wall sections 31. Thus, as the piston is raised during the desired time interval of the detent action, the limit of such interval will be determined by movement of the piston wall portions past the tops of the cylinder wall portions, at which time free flow of fluid under the piston will be permitted through the channels 38, thus permitting a quick upper movement of the piston at the'limit of its desired detent action, to'procure the required operation of the piston stem. The piston is held against rotation in the cylinder by lugs 39, projecting from its peripheral portion into certain of the channels 38, the width of said lugs be-. ing, however, less than the width ofthe channels, so as not to interfere with free flow of fluid through the channels in the release action.

The operating fluid of the dash-pot is preferably oil, although a gaseous fluid may be provided.

' By providing nested-sets of dash-pot chambers in mutual communication to dedecided advantages of compactness, and inasmuch as I utilize the spaces between my various wall sections as paths for the fluid, instead of endeavoring to render the surface relations fluid tight by accurate machining,

ll procure a decided economy in the construction of the dash-pot by the elimination of such accurate machining, and I have thus foundin practice that the piston and cylinder parts may be simply die cast and then fitted together without machining to procure their desired eificient operation. At the same time, the further important advantage exists, that this construction permits a certain lateral play of the piston stem, which prevents its binding against the parts engaged thereby in its path of travel. Also, by reason of the relatively short stroke, together with the free movement at the end of the stroke, a prompt yielding of the dash-pot under excessive conditions of stress is facilitated, so that, in the instance of the present switch structure, the switch may be broken most promptly upon the occurrence of a highly abnormal overload. chambers defined by the sliding interfit of In the present structure, the stem or plunger of the piston comprises a pair of adjustably connected parts, the upper part constitutlng I sleeve 12, in the form of a cylindrical member 40, having a bore in its lower end portion, threaded to receive a screw 4:1,which constitutes the lower section of the stem, the head of the screw being preferably cast in the piston body. The upper portion of the armature core 40 is chambered to receive a retaining Wire member 42, bent in inverted U shape, the lower end portion of one of the legs being further bent in the form of an eye 43', embracing the screw 41, while. the other end of the leg is extended within a longitudinal slot 44, formed in the side of the core member, the lower end of said leg being bowed inwardly andconstituting a pawl engageable with the screw and adapted to yield'ably set in a longitudinal groove 45 cut in thescrew, whereby thecore member is yieldablyheld against movement on the screw, the sides of the slot 44 bracing the wire pawl portion against'distortionr The upper end of the core member is closed by a cap plate 46, set within its chamber, and retaining the spring in place.

'The extent to which the armature core projects into the coil in the initial or depressed position of the dash-pot plunger obviously determines the action of the dashpot mechanism with respect to the amount an armature core engageable in the of current passing through the coil, and the core member may thus be set by adjustment on the screw for the desired operation of the dash-pot mechanism at different rates of current. This adjustment can be conveniently effected by 'simply swinging the holding yoke 25 of the dash-pot cylinder to one side, to permit removal of the cylinder,

and then grasping and turning the core member, the piston being held against the turning movement by its. lugs 39, as described. This adjustment may be thus effected in a most ready manner without necessitating manipulation of any set screws or other holding members and withoutdisturbing the interior of the dash-pot cylinder.

The periphery of the core member is provided with a series of calibrated graduations 47, whereby it may be set for proper operation under given current conditions, said graduations being read from the edge of the plate 24. The time interval of operation of the dash-pot with respect to a given set of current conditions, is adjusted as described, by means of the valve plate 37, access to said plate being aflorded by forcing the top plate 24 from the cylinder, which may be readily done by reason of its frictional fit.

I have thus provided an exceedingly compact and efiicient dash-pot control mechanismywhich is of simple and durable construction and which may be most conveniently adjusted for the various conditions of use required.

The device constituting the present embodiment of my invention is commonly termed an overload relay switch, and in use thereof, the solenoid coil 11 would beconnected in series with a motor or the like, and the contact members of the device would be connected in series with the coil circuit of the main controlling switch. The dash-pot mechanism; afl'ords an inverse time limit on the operation of the switch, causing the actuating armature core 40 to move slowly on a mild overload and permitting its very rapid movement on a serious overload. This time limit feature makes it possible to set the switch so as to protect the motor against bona fide, dangerous overload and yet prevent operation of the switch and consequent stopping of the motor incidental to temporary, trivial overload conditions, the detent action of the switch also serving to prevent its operation during the relatively heavy current period necessary in starting a motor.

While I have shown and described a preferred embodiment of my inventiomit will be appreciated that various changes and modifications of structu e and relation may be'employed, to meet differing conditions of use and manufacture, and that various phases of my invention may be employed independently of the specific mechanism described without departing in any manner from the spirit of my invention, as defined by the appended claims.

What I claim is: j

1. In. ajcontrol mechanism, the combination of a fluid container, a piston movable in said container and adapted to permit restricted flow of fluid therepast, incidental to its movement, means for causing said fluid to flow in a tortuous path during a portion of the movement of the piston, and means for permitting free flow of fluid past the piston during the remainder of said movement. I

2. In a control mechanism, the comb-ination of a fluid container, and a piston movable in said container and'adapted to permit stricted flow of fluid therepast, incidental to said movement, said container being pr0 vided with grooves extending through portions of its inner surface, whereby to permit free passage of fluid past the piston during certain movement of said piston.

3. In a control mechanism, the combination of a fluid container, a piston movable in said container, and slidably interfitting wall portions carried by the piston and container, and defining dash-pot chambers at the ends of said wall portions, having com munication between theopposed surfaces of the wall portions.

4. In a control mechanism, the combination of a fluid container, 2. piston movable in said fluid container, concentric annular wall sections at one end of the fluid container, concentric annular wall sections ear ried by the piston and slidably interfltting with the first named wall sections to define dash-pot chambers at the ends of the various wall sections in mutual communication between the opposed surfaces of the wall sections, and ports extending through the piston and communicating with adjacent dashpot chambers. a

5..In a control mechanism, the combination of a fluid container, apiston movable in said fluid container, concentric annular wall sections at one end of the fluid container, concentric annular wall sections carried by the piston andslidably interfitting with the'first named wall sectionsto define dash-pot chambers at the ends of the various wall sections in mutual communication between the opposed surfaces of the wall sections, ports extending through the piston and communicating with adjacent dash-pot with the first named wall sections to define dash-pot chambers at the ends of the various wall sections in mutual communication between the opposed surfaces of the wall sections, ports extending through the piston and communicating with adjacent dash-pot chambers, and a common means controlling the flow of fluid through said ports.

7. In a control mechanism, the combination of a fluid container, a piston movable in said fluid-container, concentric. annular wall sections at one end of the fluid container, concentric annular wall sections carried by the piston and slidably interfitting with the first named wall sections to define dash-pot chambers at the ends of the various wall sections in mutual communication between the opposed surfaces of the wall sections, ports extending through the piston and communicating with adjacent dash-pot chambers, and a plate pivoted on the piston and adapted to have its edge portions extend across the ports to adjust the capacity of said ports.-

8. In a control mechanism, the combination of a fluid container, a piston movable in said fluid container, concentric annular wall sections at one end. of the fluid container, concentric annular wall sections carried by the piston and slidably interfitting .with the first named wall sections to define dash-pot chambers at the ends of the various wall sections in mutual communication.

between the opposed surfaces of the wall sections, inlet ports extending through the piston and communicating with adjacent dash-pot chambers and valve controlled out-- let ports extending through the piston and communicating with said dash-pot chambers.

9. In a control mechanism, the combinanation of fluid. container, a piston movable in said container, a plurality of spaced concentric wall sections at one end of the container, a plurality of spaced concentric wall sections carried by the piston and slidably interfitting with the first named wall sections and the main wall of the container, whereby to define dash-pot chambers at the ends of the various wall portions in communication between the opposed surfaces of the wall portions, a central projection on the piston engaging within the innermost container carried wall section and ports extending through the piston and communicating with adjacent dash-pot chambers.

10. In a control mechanism, the combination of a fluid container, a plurality of annular concentric wall sections in one end of the container, a piston slidable in the container, concentric annular wallsections carried by the piston and slidably. interfitting with the first named wall sections 'to define dash-pot chambers at the ends of the wall sections in communication between the opposed surfaces of the wall sections, and bypass channels in the inner periphery of the fluid container extending from subhaving a plunger adapted to extend through said aperture and a yoke member having its legs pivotally connected with the fr otally connected with the frame member and having its bight portion adapted to' engage the rib and seat in said recess thereof.

13. In a control mechanism, the combination of a frame member provided with a' plunger aperture, a dash-pot engageable against'the frame member, a piston in the dash-pot having a plunger adapted to. ex-' tend through said aperture, and a yoke member formed of a single length of resilient wire having the ends of its legs bent to pivotally engage the frame member, the intermediate portions of said legs being bent in sinuous shape and the bight portion of the yoke member being engageable about the end of the dash-pot.

14. In a control mechanism, the combination of a frame member provided with a plunger aperture, a dash-pot engageable against the frame member, a piston in the a plunger adapted to exdash-pot having tend through said aperture, a pair of ribs on the end of the dash-pot, having their surfaces curved and provided with substantially central recesses, and a yoke member formed of a single length of wire having the end of its legs bent to pivotally engage the frame member, intermediate portions ,of the legs being sinuously bent, the bight portion of the yoke member being slidably engageable on the ribs to seat in the recesses thereof, and the wire of the bight portion between said ribs being bent outwardly to form a finger piece. g

15. In a control mechanism, the combina tion of a frame member provided with a plunger aperture, a shoulder surrounding said aperture, a dash-pot having an end portion'recessed to define an annular shoulder engageable about said first named shoul- .der, a piston in the dash-pot having a' plunger extending through the aperture of the frame member and readily detachable means for holding the dash-pot against the frame member. 1

16. In a control mechanism, the combinaeel tion of a frame member provided with a plunger aperture, a shoulder surrounding said aperture, a cup shaped dash-pot container member, a plate detachably fitted at the mouth of said chamber and having its central portion depressed to form a shoulder surrounding the first named shoulder, a piston in the dash-pot having a plunger ex,-

tending throu h the aperture of the frame member andv etacha'ble means for holding the dash-pot against the frame member.

17. 'In a control mechanism, the combina- 5 tion of a fixed member, a movable member, said members having interfitting irregular faces, and afilm of fluid normally separating said members to resist movement of the movable member away from the fixed member.

In testimony that I claim the foregoing I have hereunto set my hand at Milwaukee, in the county of Milwaukee and State of Wisconsin.

e. o. WILMS. 

